The present invention relates to an energy efficient light switch and more particularly to a switch which enables the automatic control of all, none or one half of the lights in a bounded area by the detection of infrared energy radiated by people working in that area.
The laws of some states require the installation of two light switches in the construction or reconstruction of individual offices. The two light switches each control a different half of the overhead lighting in a given office area. The reasoning behind such laws is that in the interest of energy conservation, employees may be offered the opportunity to use one half of the light they would normally require in their day-to-day activities. An employee may, upon entering the room and dependent upon the amount of ambient light available, select to use only one half of the bank of lights.
Further, employees may tailor the light needs to their activities and location in the room. For example, employees working at their desks would require only light in that area during the work day, while other areas of their office would not require additional artificial lighting. Energy conservation is a critical national and worldwide issue. Utilizing office lighting such that only 50% is used day-to-day results in enormous energy savings.
However, the goals of dual light switch codes are often defeated by the failure of the individual employee to use only one of the two available switches. In most instances, the employee automatically activates both light switches upon entering a room enabling both banks of lights. The employee does not take notice of the ambient light available through windows or other sources and so wastes up to 50% of the lighting energy.
It would be advantageous to have an automatically energy efficient switch that would be activated when the infrared radiated by an occupant is detected, thereby activating only one half of the lighting available in the room.
It would be further advantageous to have an automatically activated energy efficient switch that would selectively activate the lights in an office thereby providing a non-glare atmosphere for specified work stations. For example, in some work environments a computer work station having a cathode ray tube or color monitor can be illuminated without glare only when a limited number of lights in the room are activated.
Infrared detectors are well known. Passive, as well as active, infrared detectors have been used extensively to detect thermal gradient changes generated in a room by people or animals. It would be advantageous to incorporate a simple passive infrared detector into a light switch configuration, replacing existing wall-mounted light switches. Such a detector does not emit infrared energies, but passively receives any infrared energies radiated by the sweep area under detection. A passive system incorporating two detectors would be operable to provide a device having a field of view or sweep of approximately 170.degree. to 180.degree..